fix: primitive vec fast-path skip bug + release 0.10.26

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 2026-03-18
+
+### Candid 0.10.26
+
+* Bug fixes:
+  + Fix decoding failure when a trailing argument is a primitive vector
+
 ## 2026-03-16
 
 ### Candid 0.10.25

rust/candid/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "candid"
 # sync with the version in `candid_derive/Cargo.toml`
-version = "0.10.25"
+version = "0.10.26"
 edition = "2021"
 rust-version.workspace = true
 authors = ["DFINITY Team"]
@@ -16,7 +16,7 @@ keywords = ["internet-computer", "idl", "candid", "dfinity"]
 include = ["src", "Cargo.toml", "LICENSE", "README.md"]
 
 [dependencies]
-candid_derive = { path = "../candid_derive", version = "=0.10.25" }
+candid_derive = { path = "../candid_derive", version = "=0.10.26" }
 ic_principal = { path = "../ic_principal", version = "0.1.0" }
 binread = { version = "2.2", features = ["debug_template"] }
 byteorder = "1.5.0"

rust/candid/src/de.rs

@@ -1241,14 +1241,12 @@ impl<'de> de::SeqAccess<'de> for Compound<'_, 'de> {
                     return Ok(None);
                 }
                 *len -= 1;
-                if exact_primitive.is_some() {
-                    seed.deserialize(&mut *self.de).map(Some)
-                } else {
+                self.de.expect_type = expect.clone();
+                self.de.wire_type = wire.clone();
+                if exact_primitive.is_none() {
                     self.de.add_cost(3)?;
-                    self.de.expect_type = expect.clone();
-                    self.de.wire_type = wire.clone();
-                    seed.deserialize(&mut *self.de).map(Some)
                 }
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Style::Struct {
                 ref expect,

rust/candid/tests/compatibility_vectors.rs

@@ -76,3 +76,12 @@ fn bulk_encode_primitive_vectors_round_trip() {
     let empty: Vec<i32> = vec![];
     assert_eq!(Decode!(&Encode!(&empty).unwrap(), Vec<i32>).unwrap(), empty);
 }
+
+#[test]
+fn primitive_vector_is_extra_args() {
+    let extra = vec![1i16, 2, 3];
+    let bytes = Encode!(&123u8, &extra).unwrap();
+
+    let decoded_values = Decode!(&bytes, u8).unwrap();
+    assert_eq!(decoded_values, 123);
+}

rust/candid_derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "candid_derive"
 # sync with the version in `candid/Cargo.toml`
-version = "0.10.25"
+version = "0.10.26"
 edition = "2021"
 rust-version.workspace = true
 authors = ["DFINITY Team"]